Hi there! Thank you for your question. Allow me to explain about colon cancer and the test is involved colorectal cancer is the most important gastrointestinal malignancy. There are 3 locations where colorectal cancer can occur :

1.Right sided cancer - usually present with asymptomatically or anaemia symptoms due to chronic low grade bleeding
2. Left sided cancer - usually present with constipation, rectal bleeding, colicky or dull aching pain.
3. Rectal cancer – presents with early morning diarrhea, pain, feeling of incomplete defecation (tenesmus) or bleeding at the end of defecation

Screening test are done in patients about 50 withor without symptoms. CEA (carcinoembryonic antigen is a substance that’s made by cancerous tumor cells. Sometimes antigens are released into the bloodstream. The CEA test measures the amount of CEA in the blood.

CEA levels are is recommended in the symptomatic individuals as a screening method but doctors don’t use the CEA test to make a first-time diagnosis of cancer. This test isn’t an accurate way to screen for it because many other diseases can cause the levels of this protein to rise. The test can often help predict whether the cancer is growing or spreading to other parts of your body once a diagnosis has been made.

It can also help tell how well your treatment has worked and predict your prognosis. If then symptoms mentioned above are present and colorectal cancer is suspected during screening, several investigations can be done:

1. Colonoscopy (gold standard and most commonly done)
2. Double contrast barium enema (if colonoscopy can’t be done)
3. Rectal ultrasound
4. Ultrasound of abdomen (to check for spread of tumour)
5. CT scan of chest and abdomen (to check for spread of tumour)
6. Chest X-ray (to check for spread of tumour)

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